EXHIBITS 5.1, 8.1 & 23.1

                   [Letterhead of Thacher Proffitt & Wood llp]



                                                                  April 28, 2005


Greenwich Capital Markets, Inc.              WaMu Capital Corp.
600 Steamboat Road                           1201 Third Avenue
Greenwich, Connecticut 06830                 Mail Stop WMT 0626
                                             Seattle, Washington 98101
Morgan Keegan & Company, Inc.
50 North Front Street, 16th Floor
Memphis, TN  38103

                    Opinion: Underwriting Agreement (Tax)
                    Financial Asset Securities Corp.
                    First Franklin Mortgage Loan Trust 2005-FF4
                    Asset-Backed Certificates, Series 2005-FF4
                    ------------------------------------------

Ladies and Gentlemen:

We have acted as counsel to Greenwich Capital Financial Products, Inc. (the
"Seller"), Financial Asset Securities Corp. (the "Depositor") and Greenwich
Capital Markets, Inc. ("GCM", the "Initial Purchaser"; together with WaMu
Capital Corp. and Morgan Keegan & Company, Inc., the "Underwriters") in
connection with (i) the Mortgage Loan Purchase Agreement, dated April 20, 2005
(the "Seller Sale Agreement"), between the Seller and the Depositor, (ii) the
Pooling and Servicing Agreement, dated as of April 1, 2005 (the "Pooling and
Servicing Agreement"), among the Depositor, National City Home Loan Services,
Inc., (the "Servicer") and Deutsche Bank National Trust Company (the "Trustee"),
and the certificates issued pursuant thereto designated as First Franklin
Mortgage Loan Trust 2005-FF4, Asset-Backed Certificates, Series 2005-FF4 (the
"Certificates"), (iii) the Underwriting Agreement, dated April 20, 2005 (the
"Underwriting Agreement"), among the Depositor and the Underwriters, and (iv)
the Prospectus Supplement, dated April 20, 2005 (the "Prospectus Supplement"),
and the Prospectus to which it relates, dated February 22, 2005 (the "Base
Prospectus"; together with the Prospectus Supplement, the "Prospectus"). The
Mortgage Loan Purchase Agreement, the Pooling and Servicing Agreement and the
Underwriting Agreement are collectively referred to herein as the "Agreements."
Capitalized terms not defined herein have the meanings assigned to them in the
Agreements.

            In rendering this opinion letter, as to relevant factual matters we
have examined the documents described above and such other documents as we have
deemed necessary including, where we have deemed appropriate, representations or
certifications of officers of parties thereto or public officials. In rendering
this opinion letter, except for the matters that are specifically






addressed in the opinions expressed below, with your permission we have assumed,
and are relying thereon without independent investigation, (i) the authenticity
of all documents submitted to us as originals or as copies thereof, and the
conformity to the originals of all documents submitted to us as copies, (ii) the
necessary entity formation and continuing existence in the jurisdiction of
formation, and the necessary licensing and qualification in all jurisdictions,
of all parties to all documents, (iii) the necessary authorization, execution,
delivery and enforceability of all documents, and the necessary entity power
with respect thereto, and (iv) that there is not any other agreement that
modifies or supplements the agreements expressed in any document to which this
opinion letter relates and that renders any of the opinions expressed below
inconsistent with such document as so modified or supplemented. In rendering
this opinion letter, except for the matters that are specifically addressed in
the opinions expressed below, we have made no inquiry, have conducted no
investigation and assume no responsibility with respect to (a) the accuracy of
and compliance by the parties thereto with the representations, warranties and
covenants as to factual matters contained in any document or (b) the conformity
of the underlying assets and related documents to the requirements of any
agreement to which this opinion letter relates.

            This opinion letter is based upon our review of the documents
referred to herein. We have conducted no independent investigation with respect
to the facts contained in such documents and relied upon in rendering this
opinion letter. We also note that we do not represent any of the parties to the
transactions to which this opinion letter relates or any of their affiliates in
connection with matters other than certain transactions. However, the attorneys
in this firm who are directly involved in the representation of parties to the
transactions to which this opinion letter relates, after such consultation with
such other attorneys in this firm as they deemed appropriate, have no actual
present knowledge of the inaccuracy of any fact relied upon in rendering this
opinion letter.

            In rendering this opinion letter, we do not express any opinion
concerning any law other than the federal income tax laws of the United States,
including without limitation the Internal Revenue Code of 1986, as amended, (the
"Code") applicable to a real estate mortgage investment conduit ("REMIC") We do
not express any opinion herein with respect to any matter not specifically
addressed in the opinions expressed below, including without limitation (i) any
statute, regulation or provision of law of any county, municipality or other
political subdivision or any agency or instrumentality thereof or (ii) the
securities or tax laws of any jurisdiction.

            The tax opinions set forth below are based upon the existing
provisions of applicable law and regulations issued or proposed thereunder,
published rulings and releases of applicable agencies or other governmental
bodies and existing case law, any of which or the effect of any of which could
change at any time. Any such changes may be retroactive in application and could
modify the legal conclusions upon which such opinions are based. The opinions
expressed herein are limited as described below, and we do not express any
opinion on any other legal or income tax aspect of the transactions contemplated
by the documents relating to the transaction.

            Based upon and subject to the foregoing, it is our opinion that:

            1.    Each of the Agreements to which the Seller or the Depositor is
                  a party (to the extent that the laws of the State of New York
                  are designated therein as the





                  governing law thereof), assuming the necessary power and
                  authority therefor and authorization, execution and delivery
                  thereof by the parties thereto (other than any party as to
                  which we opine to that effect herein) and the enforeability
                  thereof ( except as limited by bankruptcy and other insolvency
                  laws) against the other parties thereto, is a valid and
                  legally binding agreement under the laws of the State of New
                  York, enforceable thereunder in accordance with its terms
                  against the Depositor or the Seller, as the case may be.

            2.    The Certificates, assuming the necessary entity power and
                  authority therefor, authorization, execution, authentication
                  and delivery thereof and payment therefor in accordance with
                  the applicable Agreements, are validly issued and outstanding
                  and are entitled to the benefits of the Pooling and Servicing
                  Agreement.

            3.    Assuming the accuracy of and compliance with the factual
                  representations, covenants and other provisions of the
                  Agreements without any waiver or modification thereof, for
                  United States federal income tax purposes within the meaning
                  of the Code in effect on the date hereof, (i) each of REMIC 1,
                  REMIC 2, REMIC 3, REMIC 4 and REMIC 5 will qualify as a REMIC,
                  (ii) the REMIC 1 Regular Interests will represent ownership of
                  "regular interests" in REMIC 1, and the Class R-1 Interest
                  will constitute the sole class of "residual interests" in
                  REMIC 1, (iii) the REMIC 2 Regular Interests will represent
                  ownership of the "regular interests" in REMIC 2, and the Class
                  R-2 Interest will constitute the sole class of "residual
                  interests" in REMIC 2, (iv) the Adjustable-Rate Certificates
                  (exclusive of any right to receive payments from the Net WAC
                  Rate Carryover Reserve Account), the Class CE Interest and the
                  Class P Interest will represent ownership of "regular
                  interests" in REMIC 3 and will generally be treated as debt
                  instruments of REMIC 3, and the Class R-3 Interest will
                  constitute the sole class of "residual interests" in REMIC 3,
                  (v) the Class CE Certificates will represent ownership of the
                  "regular interests" in REMIC 4, and the Class R-4 Interest
                  will constitute the sole class of "residual interests" in
                  REMIC 4, (vi) the Class P Certificates will represent
                  ownership of the "regular interests" in REMIC 5, and the Class
                  R-5 Interest will constitute the sole class of the "residual
                  interests" in REMIC 5, (vii) the Class R Certificates will
                  represent ownership of the Class R-1 Interest, the Class R-2
                  Interest and the Class R-3 Interest and (viii) the Class R-X
                  Certificates will represent ownership of the Class R-4
                  Interest and the Class R-5 Interest.

            This opinion letter is rendered for the sole benefit of each
addressee hereof with respect to the matters specifically addressed herein, and
no other person or entity is entitled to rely hereon. Copies of this opinion
letter may not be made available, and this opinion letter may not be quoted or
referred to in any other document made available, to any other person or entity
except (i) to any applicable rating agency, institution providing credit
enhancement or liquidity support or governmental authority, (ii) to any
accountant or attorney for any person or entity entitled hereunder to rely
hereon or to whom or which this opinion letter may be made available as provided
herein, (iii) to any and all persons, without limitation, in connection with the
disclosure of the tax treatment and tax structure of the transaction (as defined
in Treasury regulation section 1.6011-4) and (iv) as otherwise required by law;
provided that none of the





foregoing is entitled to rely hereon unless an addressee hereof. We assume no
obligation to revise, supplement or withdraw this opinion letter, or otherwise
inform any addressee hereof or other person or entity, with respect to any
change occurring subsequent to the delivery hereof in any applicable fact or law
or any judicial or administrative interpretation thereof, even though such
change may affect a legal analysis or conclusion contained herein. In addition,
no attorney-client relationship exists or has existed by reason of this opinion
letter between our firm and any addressee hereof or other person or entity
except for any addressee that is identified in the first paragraph hereof as a
person or entity for which we have acted as counsel in rendering this opinion
letter. In permitting reliance hereon by any person or entity other than such an
addressee for which we have acted as counsel, we are not acting as counsel for
such other person or entity and have not assumed and are not assuming any
responsibility to advise such other person or entity with respect to the
adequacy of this opinion letter for its purposes.



                                        Very truly yours,

                                        By: /s/ THACHER PROFFITT & WOOD LLP